Embedded Systems Design, 2nd Edition

148 Embedded systems design

Address Re

g

ister 1

Address Re

g

ister 1

Register 2

Address Re

g

ister 1

Register 2

Address Re

g

ister 1

Register 2

Re

g

ister 3

Re

g

ister 3 Re

g

ister 4

Re

g

ister 1

Re

g

ister 2

Re

g

ister 3

Re

g

ister 4

Auto-incrementing access

Re

g

ister 1

Re

g

ister 2

Re

g

ister 3

Re

g

ister 4

Address

Write index

Address Data n-3 Data n-2

First access

Second access

Re

g

ister n-3

Re

g

ister n-2

Re

g

ister n-1

Re

g

ister n

Index

Combined format

This is fine for small numbers of registers but with memory

devices such as EEPROM this is not an efficient method of opera-

tion. An alternative method uses an index value which is written

to the chip, prior to accessing the data. This is known as the